The primary goal of the proposed research is to investigate the biochemical nature and function(s) of mitotic and interphase kinetochore specific chromatin components. The proposed investigations exploit the fact that many scleroderma patients produce high titer antibodies that bind specifically to mammalian and avian kinetochores and interphase kinetochore element antigens. We have recently developed methods for the solubilization of kinetochore specific antigen from isolated nuclei, and for the assay of solubilized antigen during steps of purification. Preliminary experiments suggests kinetochore specific epitopes exist on a subclass of mononucleosomes. The recently developed assay for kinetochore antigen will be used in conjunction with established biochemical and immunologic methods for the fractionation and characterization of chromatin to 1) investigate the biochemical nature of postmitotic chicken erythrocyte kinetochore chromatin, 2) identify kinetochore specific DNA sequences from chicken, and 3) develop monoclonal antibody probes to study the functions of interphase persistant kinetochore components in vivo. This project is relevant to understanding human disorders in which orderly replication, expression and transmittal of genetic information is disturbed; such as aneuploid birth defects and cancer. Further, kinetochore DNA can potentially be used as a vector for introducing stable genetic material into cells for research purposes and therapy of genetic disorders.